This invention relates to novel 2'-deoxy-5-fluorouridine derivatives and salts thereof. These compounds have a high anti-cancer activity and an excellent antiviral activity, and are useful as antitumor agents or as antiviral agents.
2'-Deoxy-5-fluorouridine (FudR) exhibits a high antitumor activity but has a high toxicity, posing a problem of being limited in safety margin.
Various 2'-deoxy-5-fluorouridine derivatives have been developed to overcome this problem. For example, Japanese Unexamined Patent Publications Nos.61,591/1985 and 106,593/1985 disclose numerous 2'-deoxy-5-fluorouridine derivatives. The disclosed 2'-deoxy-5-fluorouridine derivatives have moderated the problem to a certain extent but are not satisfactorily high in antitumor activity and are insufficient in therapeutic index, absorption and the like.
We conducted extensive research to overcome the foregoing prior art problem and successfully developed novel 2'-deoxy-5-fluorouridine derivatives which are higher in antitumor activity than conventional 2'-deoxy-5-fluorouridine derivatives and which are highly safe to human body. The present invention has been accomplished based on this novel finding.